Leafy greens are good for us nutritionally, and may even help end the pandemic. Researchers from the Johns Hopkins Children's Center have gathered compelling evidence that a chemical found in broccoli and other cruciferous vegetables may offer a new and effective way to fight both COVID-19 and the common cold.
Don't run to buy leafy vegetables - yet
Scientists call the phytochemical – a chemical derived from plants, sulforaphane. Previous studies linked sulforaphane to cancer prevention. Now, recent research reports that the compound may also inhibit the replication of SARS-CoV-2 (the virus responsible for COVID-19).
Although the results of the study published in the journal Communications Biology are very promising, the study authors say there is no need to run to buy leafy vegetables. They make it clear that more studies are needed that focus specifically on the compound's effect on humans, rather than on mice as was done in the current experiment, before scientists can know if the chemical is completely safe and effective.
The natural compound of green leaves that turns into sulforaphane is found in abundance in broccoli, Brussels sprouts, kale and cabbage. This compound was first discovered and its benefits identified by scientists at Johns Hopkins decades ago.
"When the pandemic began, our multidisciplinary research teams stopped our research on particular viruses and other bacteria to focus on potentially treating what was then a new and challenging virus for us," said senior researcher and microbiologist Dr. Lori Jones-Brando, a pediatric specialist at Johns Hopkins University School of Medicine, in a press release.
"I tested a number of compounds for anti-corona activity and decided to try the sulforaphane because it showed modest activity against other microbial factors we’re investigating," she said.
Leafy greens even work against new COVID-19 varieties
The team notes that people can extract natural sulforaphane from many common food sources, including broccoli seeds, sprouts and various plants, as well as essences or sprouts for drinking.
It's worth noting that further work done by Johns Hopkins researchers suggests that sulforaphane may help prevent cancer and infections by interfering with certain extracellular processes. In the new study, each experiment used purified and synthetic sulforaphane.
Specifically, one trial involved exposing cells to sulforaphane for a few hours before infecting them with SARS-CoV-2 and corona HCoV-OC43, a virus that causes colds, and can rarely cause pneumonia or bronchiolitis. This process reduced the virus' replication by 50% among six different strains of SARS-CoV-2 including Delta and Omicron. Researchers have found similar results among cells previously infected with viruses.
Food combined with medicines
The study authors also investigated the effect of mixing sulforaphane with Remdesivir, an antiviral drug approved for use against COVID-19. This experiment resulted in a 50% inhibition of virus replication. Scientists also believe that sulforaphane and Remdesivir interact synergistically in a number of combination ratios to reduce the viral load by 50% among cells that were infected with tested viruses.
"Historically, we have learned that the combination of multiple compounds is an ideal strategy for treating viral infections. The fact that sulforaphane and Remdesivir work better in combination than alone is very encouraging."
Antiviral ingredient
Additional tests were done on mice infected with the novel coronavirus. This process led to the discovery that giving 30 mg of sulforaphane per kilogram of body weight before infection with SARS-CoV-2 significantly reduced the characteristic decrease in body weight seen among virus-infected rodents (7.5%). This pretreatment with sulforaphane also resulted in a significant reduction in the viral load of healthy rodents (decrease of 17%) and upper respiratory tract (decrease of 9%).
"What we have found is that sulforaphane targets the HCoV-OC43 and SARS-CoV-2 viruses while helping to control the immune response," researchers said. “This versatile activity makes it an interesting compound for use against these viral infections as well as those that are caused by other human viruses."
The research team plans to conduct further studies on sulforaphane with humans. The chemical may soon become an option for the prevention or treatment of COVID-19 and other viral infections.